SUMMARY ? ABSTRACT: The ?Active Sensing? perspective posits that acquisition of sensory information is enabled by overt motor behavior (e.g., saccadic scanning) and/or covert attentional operations. Understanding active sensing is crucial for unraveling the nature of the brain's interaction with the environment. The projects in this Center, including the human ECoG studies, the more invasive cellular and cell circuit studies in monkeys, and the statistical/ computational modeling studies that interface at each level of analysis, all join to investigate how the motor and attentional systems influence and participate in sensing. Numerous findings suggest that the thalamus also plays a central role in Active Sensing and one that is far more complex than previously recognized. This underscores the value of monkey studies in this Center, because direct access to the thalamus is extremely rare in human neurophysiology. A final reason to pursue monkey studies in this center is that investigations at the cellular/circuit levels of analysis bridge the gap between ECoG measurements in humans and biophysically realistic computational modeling studies directly testing models' predictions and sharpening the physiological interpretation of electrophysiological findings in humans. Our specific aims are: AIM 1 - Investigate motor involvement in auditory sensory processing. We will test the hypotheses that 1) the motor system is a source of auditory cortical rhythms, and 2) motor and premotor regions help to actively suppress distracting information. AIM 2 - Examine extralemniscal thalamic modulation of cortical synchrony and communication. We will test the hypothesis that the thalamic Matrix plays a key role in phase reset and rhythmic entrainment in auditory cortices. AIM 3 - Define neurophysiological mechanisms generating specific ECoG signals. We will use laminar LFP/CSD and MUA profiles to identify the cell populations and physiological processes that generate ECoG components analogous to those seen under the same conditions in humans. CENTER SYNERGIES: This project interacts directly with Project 3, which uses the identical auditory tasks in human ECoG studies and also with Project 1, which uses conceptually similar, albeit visual, tasks in human ECoG studies. Supported by Core A, we will interact strongly with Project 2, to aid their implementation of laminar recording methods, and to harmonize conceptual aspects of the visual and auditory studies. Supported by Core B and Project 1 and 2's PIs we will implement r-fMRI and DTI studies in our monkeys. We will feed data to Core C for eventual sharing. Finally, we will provide data to Project 5 to help build and refine cell-circuit computational models, and adjust our studies to test model predictions as the project progresses. Ultimately, the Center's investigators plan to combine models across network and cellular circuit levels.